import java.util.*;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        int n = in.nextInt();
        int m = in.nextInt();
        TreeSet<Integer> set = new TreeSet<>();
        for (int i = 0; i < n; i++) {
            set.add(in.nextInt());
        }
        for (int i = 0; i < m; i++) {
            set.add(in.nextInt());
        }
        for (int a : set){
            System.out.print(a + " ");
        }
    }
}